Recently, the asynchronous transmission mode (ATM) system has been put into practical use as a high speed digital data transmitting system. Experiments have been made on transmitting a large amount of digital video signals by the ATM system with a good efficiency.
Note that, in the present description, a "video signal" means both of a video signal and a voice (or audio) signal in relation to this.
For example, when an ATM communication line is used to transmit a video signal reproduced from a VTR device (first VTR device) to another party using a transmitting apparatus (first transmitting apparatus) and to receive the transmitted video signal at an opposite (second) transmitting apparatus where editing work is carried out by using a VTR device (second VTR device) and an editing device, the communication for this is carried out by using a telephone in many cases. It can also be considered to perform the data communication by computers etc. in place of a telephone or in addition to a telephone.
In such a case, for the transmission of the video signal, the transmission is carried out by using the ATM communication line or the like and a telephone line is used for the call for the communication. Also in data communication by computers etc., the data communication is carried out by using the telephone line. Namely, different communication systems are necessary such as both of a communication system for transmitting a large amount of video signals and a telephone line for communication small in amount but taking a long time such as a voice call and data communication. In general, the editing work takes a long time in many cases. In addition, where the transmission of the video signal or telephone communication between distant places is carried out, the communication costs become high.
Not limited to the ATM system, in other cases as well where a digital video signal is transmitted by using another communication system, the data is reproduced on the reception side, telephone communication is performed while viewing that video, and transmission and reception of a new digital video signal is carried out, the same problem as above is encountered.